This invention relates to variable valve timing devices for automobile vehicle engines.
A variable valve timing device is known in the art in which a first rocker arm driven by a first cam for low speed and a second rocker arm driven by a second cam for high speed are provided for a valve in the intake or exhaust system of an engine, and fulcrums at the bases of the rocker arms are alternately displaced so that the rocker arms alternately assume an operative position in which the rocker arm is engaged with the respective cam and an inoperative position in which the rocker arm is not engaged with the respective cam (cf. Japanese Utility Model Application Publication No. 152308/1980). In this device, the fulcrums are, in general, displaced simultaneously in switching the operating positions of the arms. Accordingly, during the course of switching the operating positions, the arms are caused to take intermediate positions and engage the cams thereat, as a result of which an undesirable impact takes place. In other words, the high speed condition cannot be smoothly switched over to the low speed condition, and vice versa.